SmCo5 nanoparticles have promising applications in high-density magnetic storage and magnetic nanocomposites. A combination of solution-phase synthesis and calciothermic reduction shows obvious advantage for preparing rare-earth hard magnetic nanoparticles. In this process, the Sm2O3 precursor was previously prepared in organic solvent, leading to a low coercivity due to the presence of CoC in SmCo5 nanoparticles. In this paper, a facile procedure for fabricating high performance ferromagnetic, crystalline SmCo5 nanoparticles in inorganic systerh is approached. 10-40 nm SmCo5 nanoparticles have been prepared with the coercivity of 20.0 kOe by reductive annealing of amorphous Sm(OH)(3) and Co(OH)(2) precursor at 900 degrees C. Thereinto, the addition of CaO can effectively prevent the particles growth. While, polycrystalline Sm2Co17 particles with stackable sheet morphology have been obtained by reduction of crystalline Sm(OH)(3) and Co(OH)(2) at 1100 degrees C. This environmentally friendly method avoids the presence of CoC successfully and improves the coercivity up to 20.0 kOe. (C) 2014 Elsevier B.V. All rights reserved.